High-frequency hermetically-sealed circuit package

ABSTRACT

A semiconductor package includes a base substrate on which semiconductor elements are disposed; a covering member which is provided to the base substrate, which covers the semiconductor elements, and which includes an opening at an end thereof at the side of the base substrate; and a connector substrate which is provided on the base substrate in a manner that the connector substrate closes the opening, which includes a first high-frequency signal line in an area located inside the covering member for a first surface, and which includes a second high-frequency signal line on a second surface being a surface on the opposite side of the first surface, the second high-frequency signal line being electrically connected to the first high-frequency signal line; wherein the base substrate is formed in a manner that the base substrate is located away from the second high-frequency signal line.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.11/535,311, filed on Sep. 26, 2006, and is based upon and claims thebenefit of priority from the prior Japanese Patent Application No.2006-91162, filed on Mar. 29, 2006; the entire contents of both of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor package, andparticularly to a semiconductor package in which a semiconductor elementis hermetically sealed.

2. Description of the Related Art

Semiconductor packages with semiconductor elements, such ashigh-frequency semiconductor elements, have been used for varioushigh-frequency devices (for example, refer to JP-A 2001-35948 (KOKAI)).Such semiconductor packages include one (a hermetic seal package) inwhich a semiconductor element is hermetically sealed, and which includesa base substrate to which the semiconductor element is disposed; a framebody which is provided on the base substrate, and which surrounds thesemiconductor element; a lid body which is provided on the frame body;and a connector substrate which is passed through the frame body, andwhich is provided on the base substrate.

For example, as shown in FIG. 1, a connector substrate 101 is providedon a base substrate 102. The connector substrate 101 is formed ofdielectrics, and is a substrate which closes an opening 104 formed in aframe 103 which is a frame body. The connector substrate 101 includes aconvex part 105 for closing the opening 104, and a high-frequency signalline 106, which is passed through the convex part 105, is provided to asurface of the connector substrate 101. On the peripheral surface of theconnector substrate 101, an outer frame 101 a to which W paste isapplied, followed by sintering, is provided. The outer frame 101 a andthe frame 103 are brazed with Ag, and a hermetic seal package is formed.

A portion, through which the high-frequency signal line 106 penetrates,functions as a triconductor part (a stripline part) 106 a, and otherportion functions as a micro-strip line part. The triconductor part 106a of the high-frequency signal line 106 is formed thinner than themicro-strip line part in order to match impedance of the triconductorpart 106 a with that of the micro-strip line part (refer to FIG. 1).

However, recently, semiconductor packages have been developed into thosewith high power. When the width of the high-frequency signal line 106 ismade smaller, the insertion loss of a high-frequency signal isincreased, and allowable current of the high-frequency signal line 106is lowered. Consequently, there are cases where the triconductor part106 a of the high-frequency signal line 106 melts.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a semiconductor packagewith which melting of a high-frequency signal line due to high power canbe suppressed, and with which insertion loss of the high-frequencysignal is prevented from being increased.

An aspect of embodiments of the present invention is that asemiconductor package includes a base substrate on which a semiconductorelement is disposed; a covering member which is provided to the basesubstrate, which covers the semiconductor elements, and which includesan opening at an end thereof at the side of the base substrate; and aconnector substrate which is provided on the base substrate to close theopening, and which includes a first high-frequency signal line and asecond high-frequency signal line. The first high-frequency signal lineis in an area located in the covering member for a first surface. Thesecond high-frequency signal line is on a second surface which is asurface on the opposite side of the first surface, and is electricallyconnected to the first high-frequency signal line. The base substrate isformed in a manner that the base substrate is located away from thesecond high-frequency signal line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a part of a conventionalsemiconductor package;

FIG. 2 is an exploded perspective view schematically showing aconfiguration of a semiconductor package of a first embodiment of thepresent invention;

FIG. 3 is a plan view showing a part of the semiconductor package shownin FIG. 2;

FIG. 4 is a cross-sectional view taken along the A-A line in FIG. 3;

FIG. 5 is an explanatory view showing various design values of thesemiconductor package in a case of setting a characteristic impedance at50Ω;

FIG. 6 is an exploded perspective view schematically showing aconfiguration of a semiconductor package of a second embodiment of thepresent invention; and

FIG. 7 is a cross-sectional view showing a part of the semiconductorpackage shown in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described withreference to FIGS. 2 to 5.

As shown in FIGS. 2 to 4, a semiconductor package 1A of the firstembodiment of the present invention includes a base substrate 2; asemiconductor mounting part 3 which is provided on the base substrate 2,and which includes a plurality of semiconductor elements S; a coveringmember 5 which is provided to the base substrate 2, which covers therespective semiconductor elements S, and which includes an opening 4 atan end thereof at the side of the base substrate 2; and a connectorsubstrate 6 which is provided on the base substrate 2 to close theopening 4, and which includes a first high-frequency signal line 7 a anda second high-frequency signal line 7 b. The first high-frequency signalline 7 a is in an area located in the covering member 5 for a firstsurface 6 a. The second high-frequency signal line 7 b is on a secondsurface 6 b (refer to FIG. 4) which is the surface on the opposite sideof the first surface, and is electrically connected to the firsthigh-frequency signal line 7 a.

The semiconductor mounting part 3 includes the semiconductor elements S;a mounting part 3 a which supports the semiconductor elements S; twomatching condensers 3 b which are provided on the mounting part 3 a, andwhich are placed respectively on both sides of an array of thesemiconductor elements S. These matching condensers 3 b are electricallyconnected to the respective semiconductor elements S by wire bonding orthe like.

The covering member 5 includes a frame 5 a which is formed into aframe-like shape, and which is provided on the base substrate 2; and alid member 5 b which is a lid body provided on the frame 5 a. Thesemiconductor mounting part 3 is housed in the covering member 5.Thereafter, the semiconductor mounting part 3 is hermetically sealed inthe covering member 5. Two openings 4 are provided to the frame 5 a in away that the two openings 4 face each other. These openings 4 arerespectively situated on ends at the side of the base substrate 2.

The connector substrate 6 is a substrate which is formed into aplate-like shape, and which is formed of dielectrics having a certainpermittivity. The connector substrate 6 functions as a member whichcloses the openings 4 of the frame 5 a. To the first surface 6 a of theconnector substrate 6, the first high-frequency signal line 7 a isprovided in a manner that the first high-frequency signal line 7 a islocated inside the frame 5 a, and a third high-frequency signal line 7 cis provided in a manner that the third high-frequency signal line 7 c islocated outside the frame 5 a. Furthermore, the second high-frequencysignal line 7 b is provided to the back surface which is the secondsurface 6 b (refer to FIG. 4) of the connector substrate 6.

The first high-frequency signal line 7 a, the second high-frequencysignal line 7 b, and the third high-frequency signal line 7 c arerespectively transmission lines through which high-frequency signalspass. The first high-frequency signal line 7 a, the high-frequencysignal line 7 b and the high-frequency signal line 7 c are connected toone another respectively through a plurality of through-hole wirings 8formed on the connector substrate 6.

The first high-frequency signal line 7 a is extended from an internalend of the connector substrate 6, the internal end being towards thecenter inside the frame 5 a, in the direction toward an external end ofthe connector substrate 6 outside the frame 5 a, the internal end facingthe external end. The first high-frequency signal line 7 a is providedup to a position in front of the frame 5 a so as not to contacttherewith. The first high-frequency signal line 7 a is electricallyconnected to the matching condenser 3 b. The third high-frequency signalline 7 c is provided from a position in the vicinity of the frame 5 a toan external end of the connector substrate 6. The second high-frequencysignal line 7 b is electrically connected to the first high-frequencysignal line 7 a and to the third high-frequency signal line 7 c throughthe respective through-hole wirings. These first high-frequency signalline 7 a, the second high-frequency signal line 7 b, and the thirdhigh-frequency signal line 7 c are formed of, for example, a W thickfilm or a Cu thick film, Ni plating, Au plating, and the like. Thethrough-hole wirings 8 are formed into blind through-holes for ahermetic seal.

To the third high-frequency signal line 7 c, a lead wire 9 is providedto draw out the third high-frequency signal line 7 c from thesemiconductor package 1A. The lead wire 9 is electrically connected tothe third high-frequency signal line 7 c.

The base substrate 2 is a substrate formed into a plate-like shape, andsupports the back surface of the connector substrate 6, the back surfacebeing the second surface 6 b. This base substrate 2 is formed of amaterial having high heat dissipation characteristics such as copper ina way that the base substrate 2 is located away from the secondhigh-frequency signal line 7 b. That is, a concave part 2 a is providedto the base substrate 2. The concave part 2 a faces the secondhigh-frequency signal line 7 b, and is located away from the secondhigh-frequency signal line 7 b. Thus, in a case where the connectorsubstrate 6 is provided on the base substrate 2, the base substrate 2 isprevented from contacting with the second high-frequency signal line 7b.

The concave part 2 a is formed by removing a part of the base substrate2, the part having a region larger than the second high-frequency signalline 7 b, the region including a region which faces the secondhigh-frequency signal line 7 b. Because of the presence of the concavepart 2 a, a space is provided between the second high-frequency signalline 7 b and the base substrate 2. This space is filled with air, and anair layer is formed therein.

As described above, in the first embodiment of the present invention,the second high-frequency signal line 7 b is provided to the secondsurface 6 b of the connector substrate 6, and the base substrate 2 isformed in a manner that the base substrate is located away from thesecond high-frequency signal line 7 b on the second surface 6 b.Thereby, the second high-frequency signal line 7 b, which passes underthe frame 5 a, functions as a micro-strip line part. At this time, theair layer under the second high-frequency signal line 7 b is dielectrics(∈1>∈2). For this reason, in order to match impedance of the firsthigh-frequency signal line 7 a and the second high-frequency signal line7 b, and of the third high-frequency signal line 7 c and the secondhigh-frequency signal line 7 b, it is necessary to set the width W2 ofthe second high-frequency signal line 7 b larger than the widths W1respectively of the first high-frequency signal line 7 a and of thethird high-frequency signal line 7 c. Accordingly, the allowable currentof the second high-frequency signal line 7 b is increased, and meltingof the second high-frequency signal line 7 b due to high power can besuppressed. Hence, insertion loss of a high-frequency signal can beprevented from being increased.

Moreover, since a part of the base substrate 2, the part facing thesecond high-frequency signal line 7 b is thin, it is made possible tosuppress the occurrence of wraparound of a high-frequency signal at thetime when the high-frequency signal passes the lead line 9. Accordingly,a high-frequency property can be enhanced. At this time, the basesubstrate 2 is made only partially thin, and is prevented from beingmade entirely thin. Hence, the mechanical strength of the base substrate2 can be maintained.

The base substrate 2 includes the concave part 2 a which faces thesecond high-frequency signal line 7 b, and which is located awaytherefrom. Thereby, with a simple constitution, the secondhigh-frequency signal line 7 b passing under the frame 5 a can beconstituted as a micro-strip line part. Furthermore, the base substrate2 can be easily formed in a manner that the base substrate 2 is locatedaway from the second high-frequency signal line 7 b.

In this event, as shown in FIG. 3, the width of the first high-frequencysignal line 7 a is indicated as W1, the width of the secondhigh-frequency signal line 7 b as W2, and the width of the concave part2 a as W3. As shown in FIG. 4, permittivity of the connector substrate 6is set as ∈1, permittivity of air as ∈2, the thickness of the connectorsubstrate 6 as t1, and the depth of the concave part 2 a, i.e. thethickness of the air layer, as t2. In this case, when the semiconductorpackage 1A is designed with characteristic impedance set at 50Ω, variouskinds of design values are obtained as those of Example shown in FIG. 5.Incidentally, a conventional semiconductor package was used forComparative Example.

As shown in FIG. 5, in Example, the width W2 of a high-frequency signalline (the second high-frequency signal line 7 b) was 0.644 mm. InComparative Example, the width of a high-frequency signal line (atriconductor part 106 a: refer to FIG. 1) was 0.148 mm. In addition, inExample, the width of a ground conductor was the width W3 of the concavepart 2 a, and was 3.0 mm. In Comparative Example, the width of a groundconductor was infinite (the width of the base substrate 102: refer toFIG. 1). Thus, with the semiconductor package 1A, a high-frequencysignal line can be designed to have a width much larger than that of astrip line. Thereby, the allowable current of a connector part can bemade large. In addition, the third high-frequency signal line 7 c can bedesigned to have a width in the range of not less than W1 to not greaterthan W2. Thereby, the fastening strength of the lead wire 9 can beincreased. Moreover, the width of the ground conductor can be reduced bythe thickness t2 of the air layer. Hence, a favorable high-frequencyproperty can be obtained.

Second Embodiment

A second embodiment of the present invention is described with referenceto FIGS. 6 and 7.

In the second embodiment, different parts from those of the firstembodiment are described. In the following descriptions and thedrawings, the identical reference numerals are used to designate theidentical or similar components, the descriptions of which will beomitted.

As shown in FIGS. 6 and 7, to a base substrate 2 included in asemiconductor package 1B of the second embodiment of the presentinvention, a notch part 2 b is provided in place of the concave part 2 ain the first embodiment. The notch part 2 b is located away from asecond high-frequency signal line 7 b. Thereby, in a case where aconnector substrate 6 is provided on the base substrate 2, the basesubstrate 2 is prevented from contacting with the second high-frequencysignal line 7 b.

The notch part 2 b is formed by notching a part of the base substrate 2,the part having a region larger than the second high-frequency signalline 7 b, the region including a region which faces the secondhigh-frequency signal line 7 b. Because of the presence of the notchpart 2 b, a portion of the base substrate 2 in a position, which facesthe second high-frequency signal line 7 b, does not exist.

As described above, in the second embodiment of the present invention, asimilar effect as that of the first embodiment can be obtained.Furthermore, by providing the notch part 2 b to the base substrate 2, aportion of the base substrate 2 in a position, which faces the secondhigh-frequency signal line 7 b, does not exist. Thereby, the occurrenceof wraparound of a high-frequency signal at the time when thehigh-frequency signal passes a lead wire 9 can be more reliablysuppressed compared with the case of the first embodiment. In addition,the lead wire 9 can be directly connected to the second high-frequencysignal line 7 b. In this case, the third high-frequency signal line 7 cis not needed.

Incidentally, since the base substrate 2 includes the notch part 2 bformed away from the second high-frequency signal line 7 b, with asimple constitution, the second high-frequency signal line 7 b passingunder the frame 5 a can be constituted as a micro-strip line part.Furthermore, the base substrate 2 can be easily formed in a manner thatthe base substrate 2 is located away from the second high-frequencysignal line 7 b.

Other Embodiments

It is to be understood that the present invention is not limited to theabove-described embodiments, and various changes may be made thereinwithout departing from the spirit of the present invention.

For example, in the above-described embodiments, various kinds of valueshave been described. However, the values are merely illustrative and notrestrictive.

Moreover, in the above-described embodiments, respectively by way of thethrough-hole wirings 8, the second high-frequency signal line 7 b iselectrically connected to the third high-frequency signal line 7 c whichis on the first surface 6 a of the connector substrate 6, and the leadwire 9 is connected to the third high-frequency signal line 7 c. It is,however, not limited to the above. For example, the lead wire 9 may beconnected to the second high-frequency signal line 7 b without providingthe third high-frequency signal line 7 c.

1. A semiconductor package comprising: a base substrate on whichsemiconductor elements are disposed; a covering member which is providedto the base substrate, which covers the semiconductor elements, andwhich includes an opening at an end thereof at the side of the basesubstrate; and a connector substrate having a first surface and a secondsurface opposite to the first surface, the connector substrate providedon the base substrate in a manner that the connector substrate closesthe opening, which includes a first high-frequency signal line in anarea located inside the covering member on the first surface, and whichincludes a second high-frequency signal line on the second surface, thesecond high-frequency signal line being electrically connected to thefirst high-frequency signal line; wherein the first high-frequencysignal lire and the base substrate provide a first micro-strip linepart, the second high-frequency signal line and the base substrateprovide a second micro-strip line part, and impedance of the firstmicro-strip line part is the same as impedance of the second micro-stripline part.
 2. The semiconductor package according to claim 1, whereinwidth of the second high-frequency signal line is larger than width ofthe first high-frequency signal line in order to match impedance of thefirst micro-strip line part and the second micro-strip line part.
 3. Thesemiconductor package according to claim 1, wherein the base substrateof the second micro-strip line part is thinner than the base substrateof the first micro-strip line part in order to match impedance of thefirst micro-strip line part and the second micro-strip line part.
 4. Thesemiconductor package according to claim 1, wherein the base substrateis formed in a manner that the base substrate of the second micro-stripline part is located away from the second high-frequency signal line. 5.The semiconductor package according to claim 4, wherein the basesubstrate includes a concave part which keeps this base substrate of thesecond micro-strip line part away from the second high-frequency signalline.
 6. The semiconductor package according to claim 5, wherein theconcave part provides a space between the second high-frequency signalline and the base substrate of the second micro-strip line part, and thespace is filled with air.